docs: def convert_to_ip(self):
          """Convert all Data Collections of this EPW object to IP units.
  
          This is useful when one knows that all graphics produced from this
          EPW should be in Imperial units."""
          if not self.is_data_loaded:
              self._import_data()
          if self.is_ip is False:
              for coll in self._data:
                  coll.convert_to_ip()
          self._is_ip = True